how-to: calibrate the Prime eRob arms#4
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New how-to mirroring the Lite "Calibrate the zero pose" page, for the eRob (ZeroErr) EtherCAT arms. Covers what differs from Lite: CSP has no MIT zero-torque, so limp is done by writing the drive's internal loop gains; the 0x2383 "Bus Regulation of PID" gate must be on first or gain writes are ignored; damped-limp (kp=0, ki=0, keep kd) per joint; and the offset is applied by folding it into the per-joint PDO factor/offset (fold_calibration.py) rather than a software offset, since ethercat_driver is upstream. Includes the confirmed 0-9 bus-split table and the common gotchas. Added to the How-to sidebar after calibrate_zero_pose. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_019z5ubj27Me94u163g7E3ec
- Cover the 4 Sito wrists: same calibrate_erob tool + prime_calibration.yaml, backends:=can isolated sweep, and the flip-a-direction-without-resweeping formula (offset_new = offset + (lower+upper)). - Correct the Fault 4616 guidance: control_frequency MUST equal the controller_manager update_rate (ethercat_driver syncs DC from the CM loop, no separate thread). Separated from the fixed ~70s staged activation. - Drop the waist note (the 3 waist joints are fixed this version). - Fold the bring-up + tracker into one calibrate.launch.py invocation; /joint_states -> /prime/joint_states. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_019z5ubj27Me94u163g7E3ec
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New concepts/prime_hybrid_actuation.md documenting the BAR Prime bringup: the 14-DoF two-bus topology (10 eRob CiA402 over EtherCAT + 4 Sito MIT over SocketCAN), the one-controller_manager / two-ros2_control-block architecture, the control_frequency==update_rate DC rule and sequenced spawners, both impedance realizations with exact SI->actuator equations (eRob MIT-in-CSP loop gains kp/kd -> 0x2382/0x2381 gated by 0x2383; Sito MIT kp/688.58, kd/1.125), the transmission-efficiency caveat + torque_efficiency knob, the per-mode PD table, the impedance manager and its "no SDO until /prime/joint_states" 0xA000 rule, and both performance fixes (parallel-SDO mode switch 3.6s->0.46s; 1 kHz startup bring-up loop 70s->13.6s). Adds three troubleshooting entries and a Concepts sidebar entry. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_019z5ubj27Me94u163g7E3ec
Reflect the bar_description_prime -> prime_description migration (external T-K-233/Prime-Description, prime_dummy variant, like lite_description): packages reference + heading anchor, the prime_hybrid_actuation ros2_control path, the launch_args cross-link, the installation package list, and the stale hardware_specs placeholder note (Prime is now external + 14-DoF hardware-validated). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_019z5ubj27Me94u163g7E3ec
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Adds a how-to for calibrating the Prime eRob (ZeroErr) EtherCAT arms — the analog of the Lite "Calibrate the zero pose" page.
Covers the eRob-specific mechanics:
0x2383"Bus Regulation of PID" must be enabled first, or gain writes are silently ignored.factor/offset(no driver fork, no drive-NVM writes).Pairs with bar_ros2 PR #5 (the calibration toolchain). MDX-checked (no raw tags/braces/bare URLs); no Node locally so the Docusaurus build runs in CI.
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https://claude.ai/code/session_019z5ubj27Me94u163g7E3ec